Author Topic: Swingup external threading tool  (Read 106557 times)

Offline Ned Ludd

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Re: Swingup external threading tool
« Reply #50 on: December 08, 2009, 11:39:36 AM »
Hi Guys,
Can't help but think that the tool will have to rise clear of the work, even if it doesn't cut there will surely be a side ways force trying to bend the pivot. Didn't want to be the first to bring this up, the last time I commented, about the retracting tool holder, Mr Standard stopped work on it. :(
Ned Ludd
PS now found camera and charger, so will soon post piccies, I hope.
I know enough to do what I do, but the more I know the more I can do!

Leafy suburbs of NW London

Offline NickG

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Re: Swingup external threading tool
« Reply #51 on: December 08, 2009, 11:47:42 AM »
There won't be any sideways force, as the vertical component of the force (due to angle of thread and relief angle on tool) will push the tool upwards as there is nothing holding it down. So the tool should ride up a bit further on the thread flank.

Lets wait and see.

Nick
Location: County Durham (North East England)

Offline jim

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Re: Swingup external threading tool
« Reply #52 on: December 08, 2009, 12:04:14 PM »
i'm really looking forward to a vid of this in action.

looking real good :clap:
if i'd thought it through, i'd have never tried it

Offline khand

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Re: Swingup external threading tool
« Reply #53 on: December 08, 2009, 12:15:16 PM »
I made a holder for some carbide threading inserts about a month ago and was planning on making it retractable but I like your idea a lot better. Can't wait to see how this turns out.

Offline Bernd

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Re: Swingup external threading tool
« Reply #54 on: December 08, 2009, 01:43:09 PM »
Bogs,

I'm not trying to destroy the concept. I'm wondering out loud about the backlash you have in the gearing between the chuck and the carriage moving so the tool will stay in the cut slot of the thread. It's the same principle as withdrawing the cross slide and having to go past your setting and then back in to take up the backlash. That's what I was thinking about.

Bernd

Note Added: Just did a test on my Logan lathe. Set up for 20 threads. Ran machine in forward, as if cutting threads. Then reversed the motor. It took a 1/4 of a turn on the chuck before the lead screw started to turn and one full turn of the chuck before the carriage started to move.

I must have one sloppy lathe when it comes to back lash then.
« Last Edit: December 08, 2009, 01:55:07 PM by Bernd »
You can't fix "STUPID".

Offline AdeV

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Re: Swingup external threading tool
« Reply #55 on: December 08, 2009, 03:21:00 PM »
[deleted due to off-topicness]
« Last Edit: December 10, 2009, 02:05:08 PM by AdeV »
Cheers!
Ade.
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Or: Zhengzhou, China. An even longer way from anywhere...
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bogstandard

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Re: Swingup external threading tool
« Reply #56 on: December 10, 2009, 12:55:28 PM »
I have now unlocked this topic again, to show you what has happened on the testing.

I could only manage an hour this afternoon so not much to show, but a lot to talk about.

I had set everything up as I would normally set up for threading, using the normal offset method. I set the lathe to cut a 2mm pitch.
A lump of 1" nylon bar was used for the first cuts, if something was going to go drastically wrong, I didn't want my tipped cutting tool damaged.
Everything worked exactly as planned, it cut the thread perfectly and when the lathe was flipped into reverse, the tooltip lifted, wound back to off the job and duly dropped down into the cutting position again. I carried on for a few more cuts, and nothing changed, it behaved perfectly.
This now gave me a little more confidence in what I was doing, so then I thought that it was time to give it a good try out.




Raiding my steel recycle box, I came up with some of the worst crap to thread, a length of 7/8" diameter steel conduit. This stuff is made from the dregs of the steel world. I was expecting major problems.

So after mounting it up, it was threaded the same way as I had done the nylon, with exactly the same results, except that the finished threads were real rough, but I had expected that because of the material, it is no better when you thread it up with a die when fitting it up in a factory.
There was no chatter, jumping or farting, in fact nothing out of the ordinary, except it only took me a fraction of the time it would normally take.




So after a quickie switchover, I swapped it to 5mm pitch, and carried out the same exercise on the other end of the pipe. I couldn't go any deeper otherwise I would have been thru the tube wall.

Results.

This is getting monotonous, exactly the same as before.



Conclusions after this very short trial.

This really wasn't a full trial, but an initial proving run. Until smaller threads are cut then a final conclusion cannot be forecast, but if it goes like these three have gone, it should mean that this concept is definitely a winner, and could be designed to be made much simpler.

I found that when using it, I sat on my stool, with one foot on the brake and one hand on the fwds/rev lever. It was so simple to do, put on cut using topslide, start the machine fwds, stop when at end of cut, flip machine into reverse, run off the end of job then stop, repeat process. In fact it is easier than trying to use the drop in dial, no waiting about or counting. So for me, I will use this method all the time, rather than mucking about with other settings.

I have now to make a camera mount to video the process and to prove the concept on other materials and sizes.

BTW, after seeing how the swarf behaved, I don't think that will be a problem at all.

Now gents, is the time for your criticism, worries and conclusion jumping.


Bogs



Offline Bernd

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Re: Swingup external threading tool
« Reply #57 on: December 10, 2009, 01:14:58 PM »
Bog's

Well, I was proved wrong in thinking that the backlash of the machine would mess up the threads. I was thinking that with the backlash of my machine that it would take the tops off of the thread going in reverse. I came away with that conclusion because I used the regular way of mounting a cutting tool, or solid mount and ran the machine backwards after having it set up to 8 threads per inch. When reversing it the carriage didn't start moving until I was half way between the threads. Thus the conclusion that the tool needed to be rasied all the way above the part manually.

I now stand corrected on that matter of thinking. Perhaps you have some insight as to why I would have thought this? (yes I know what you'd like to call me, but be kind please)

And thanks for finishing the thread. I really didn't want to build a tool and prove that my thinking was in error.  :nrocks:

Regards,
Bernd
You can't fix "STUPID".

Rob.Wilson

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Re: Swingup external threading tool
« Reply #58 on: December 10, 2009, 01:27:52 PM »
 Nice one Bog's    :headbang: :headbang: :headbang: :headbang:


Regards Rob

Offline Divided he ad

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Re: Swingup external threading tool
« Reply #59 on: December 10, 2009, 02:06:26 PM »
Job done!


Awaiting full trial testing..... When ever, I've never even tried threading! This is pure curiosity for me  :)





Ralph.
I know what I know and need to know more!!!

bogstandard

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Re: Swingup external threading tool
« Reply #60 on: December 10, 2009, 03:59:40 PM »
Bernd,

I wasn't really angry, and the reason I locked the post was to prevent any more people jumping to unfounded conclusions, before we had a look at what the tool actually does, rather than assuming what it would do.

I think a few people could have got themselves into an apology situation, including myself, when of course that isn't what posting on here is all about.

With regards to your backlash worry. I actually set my machine gearset up a little loose to give me that condition from the start, not a lot, but enough, and I have to tell you that I found nothing to worry about on that score. But I did retract a little more than I would normally do (about 1" past the end) just to make sure it was in synch again before it took the next cut.

I am going to try cutting down to 1/8" diameter bar, just to see if the weight of the supported tool causes any problems with bending of the said piece of metal. If it can do that small, then I think that will satisfy most needs. Also to be done is left hand threading, but I expect no problems at all with that. I would really like to do a very large thread as well, but I will have to see what spare metal I have that I can afford to waste on these trials.


I am so happy with how it went this afternoon, I've still got a silly grin from ear to ear. Just hope it doesn't get knocked off by the next bit.


Bogs

I had forgotten to thanks Rob and Ralph for the comments, but also to say to Ralph, if this does turn out as planned, it could make threading for people like yourself much easier, as long as you have a lathe that reverses.
« Last Edit: December 10, 2009, 04:07:03 PM by bogstandard »

Offline ariz

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Re: Swingup external threading tool
« Reply #61 on: December 10, 2009, 04:28:11 PM »
I'm happy to see that everything went well with the test, because this sort of threading (making a thread) is the only one that I use: fwd, stop, retract, bckwd, stop, etc. without disengaging the gear
so, this very useful tool will be on top of my to-do list
thank you bogs (and everyone who contributed)  :nrocks:




Offline Bernd

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Re: Swingup external threading tool
« Reply #62 on: December 10, 2009, 06:20:14 PM »
Bog's

I'm glad the tool is working out.

I did learn one valueable lesson from this though, and that is shut up untill the test results are in.  :)

Bernd
You can't fix "STUPID".

Offline John Stevenson

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Re: Swingup external threading tool
« Reply #63 on: December 10, 2009, 07:13:59 PM »
What about stopping a tipped tool in the cut without the help of a run off groove ? That part sounds like the recipe for a chipped tool.

John S.
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Offline Ned Ludd

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Re: Swingup external threading tool
« Reply #64 on: December 10, 2009, 07:47:01 PM »
Hi Mr. Standard,
I can't tell you delighted I am that the tool worked well.  :clap:
I am always pleased to be proved wrong, as long as the net result is greater overall knowledge.
Glad to have you back.
Ned Ludd
I know enough to do what I do, but the more I know the more I can do!

Leafy suburbs of NW London

bogstandard

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Re: Swingup external threading tool
« Reply #65 on: December 10, 2009, 11:00:56 PM »
Quote
What about stopping a tipped tool in the cut without the help of a run off groove ? That part sounds like the recipe for a chipped tool.

I just knew John  would pick up on something I had done. But I did have an excuse, I rushed all these threads thru with the bare minimum of preparation, otherwise you wouldn't have got any results at all.

I have Stew calling round later today, so I suppose I will have to prepare a part for giving him a demo, and I promise to have the correct depth runout slot.


John

Offline andyf

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Re: Swingup external threading tool
« Reply #66 on: December 11, 2009, 06:23:18 AM »
It's starting to look pretty effective, Bogs - great! As to 1/8" stock, I doubt that the weight of the tool and its holder would cause any problems when reversing. To my mind, the force exerted on the stock involved must be much less than when actually cutting a thread into the same size stock. But I suppose that a practical test will reveal whether it works as well on slender stuff, and in cutting small pitches.

Quote
I have now to make a camera mount to video the process
Quote
I have Stew calling round later today, so I suppose I will have to prepare a part for giving him a demo
Maybe Stew could be prevailed upon to act as a camera tripod bipod   :)

Andy
Sale, Cheshire
I've cut the end off it twice, but it's still too short

bogstandard

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Re: Swingup external threading tool
« Reply #67 on: December 11, 2009, 10:56:28 AM »
Andy,

We tried that, but Stew seemed to be a bit of a jinx and we could only get a 14 second clip each time we tried.

So one piccy and a 14 second clip is all you are getting this time.

I managed to find a lump of 2.5" brass that I could cut a thread on. So away I went and cut a 5mm pitch on it, which is near enough to a 5 tpi thread for comparison. The holder I have made caused a problem in that the top overhang wouldn't allow the tool to come up high enough for really large threads, but that is a problem that can easily be overcome. But with a little coaxing we got it done. Other than that, the cutting action couldn't be faulted, it just went ahead and did it, just as planned.



And for all you video nuts, this is as much as it would record each time, so this will have to do you until I can work out what is wrong with the camera settings. But at least it shows the full cutting and retraction action, just.



Stew can be my independant witness that the tool really does work (otherwise he doesn't get the free beer at Christmas).


Bogs

Offline NickG

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Re: Swingup external threading tool
« Reply #68 on: December 11, 2009, 11:02:00 AM »
Nice video Bogs, it did exactly what I thought  :clap:  :beer:
Location: County Durham (North East England)

Offline sbwhart

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Re: Swingup external threading tool
« Reply #69 on: December 11, 2009, 11:08:11 AM »
Stew the bipod reporting in.

All worked perfectly, that course thread was a real tester with a little bit of tunning John had it working real nice.

The worst problem was from my driving ability of the camera "but i only pressed the button once John"  "it should record more than that lets have another go" "honestly John I only pessed it once" "somthings wrong lets have another go" :-------------------------

And then John spilt blood when he slipped and craked his shin on his machine stand

  OUCH

 :( :( :(

I learnt a few new RAF words

 :D :D :D

Stew

A little bit of clearance never got in the road
 :wave:

Location:- Crewe Cheshire

Rob.Wilson

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Re: Swingup external threading tool
« Reply #70 on: December 11, 2009, 11:54:50 AM »
Great job Bog's 

The tool works a treat  :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap: :clap:

Regards Rob

Offline khand

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Re: Swingup external threading tool
« Reply #71 on: December 11, 2009, 01:06:35 PM »
I knew it was going to work. Nice job. :clap: :clap: :clap: :clap: :clap:

Offline Bernd

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Re: Swingup external threading tool
« Reply #72 on: December 11, 2009, 02:42:44 PM »
Very nice indeed. I like the way that tool pops up when it reverses. Sure looks like it'll make thread cutting faster and easier.  :thumbup:  :clap:  :clap:  :clap:  :clap:

Can't believe how fast your lathe stops. Is there a brake on it? Also there seems to be no backlash from the time the chuck reverses and the carriage starts to move backwards.

This going to get me to look at why I've got so much slop in the drive train. :scratch:

Stew, you do make a nice bipod.  :lol:

Bernd

You can't fix "STUPID".

Offline jim

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Re: Swingup external threading tool
« Reply #73 on: December 11, 2009, 02:48:26 PM »
 :clap: :clap: :clap:

very impressive,  :thumbup: :thumbup:
if i'd thought it through, i'd have never tried it

Offline gingerneer

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Re: Swingup external threading tool
« Reply #74 on: December 11, 2009, 04:23:03 PM »
Thats neat, yet another project added to the list.